Aeronautical propeller and method of making same



Nov. 10,1931.

.A/ERONAUTICALAPROPELLER AND METHOD OF MAKING SAME Filed Deo.' 2l, 1928Y' iHWENTOR. BYSYLVANUS .PEER

A lA TToRNE/ vof sizes and shapes. l

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Patented Nov. 10, l1.931

UNITED STATES SYL'VANUS A; REED, OF YORK, N. Y., ASSIGNOR TO `THE REEDPROPELLER CO. IN C., 0F NEW YORK, N. Y., A. CORPORATION OF NEW YORK l`irsral'a'r OFFICE .umoNAUmoaL PROPELLER AND METHOD or MAKING sansapplication moa nooombor a1, 192s. sor'iol no. 327.507.-

My invention relates in general to aeronautical propellers and a methodof making the same, and has reference more particularly to the t pe. ofmetalv propeller blades disclosed in S. Patents Nos. 1,463,556 and1,518,410, granted to me July 31, 1923, and December 9,1924, resectively, and in which the blades are prefera ly solid and of forgedstrong light weight metal alloy and thin relatively to their thrustloads.

In'making propellers of this type of very large diameters, such as maybe used on motors geared down to a slower propeller rotation, there aremanufacturing diiliculties and much expense is also involved. I have nowdevised a novel form of this type of propel- 1er which can be made fromrolled Ametal plates of much less thickness than the maxi' imum bladethickness', and which plates are staple articles of commerce of moderatecost and furthermore such plates are easily and cheaply and safely cutand bent to make up different propeller desi s of a large range yinvention also includes a method of making the peculiar construction ofblades comprising forked-endl interlocking elements, so that they may bereadily put together and secured in operative form in a propellerstructure. Other 'impor-- ltant advantages possessed by my ,improve-lIments will appear from the detailed description hereinafter given.v

I have.illustrated"types of my improved propeller structure in theaccompanying drawings, wherein;

4Figure lshows a plan view of a blank of Y my improved blade, thedotted-line zone showin the parts of the fork-prongs which are to gebent around the opposite sides of the axis of rotation. v Figure 2 isasimilar view. to that of Fig. 1, showing the blankwith its fork-prongsbent into o cate thereof.

A Fi re 3 is a similar view to that of Fig. 2 the viewv being taken`atfright-angles to said Figure 4 shows a side viewof a completed roller made from two duplicate aemle gblades, the View being taken lookingin\ rm for assemblage with a dupli-` tho lino of the axis of rotationmid through v the central opening which receivesthe hub.

Figure 5 is a. similar view to vthat shown in i v Fig. 4, but atright-anglesthereto Aand with the hub structure added to the propeller.

Figure 6 shows an end View ofthe hubstructure with -portions of theconnected blades shown as broken away.

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Figures -7 and 8, respectively, show crossmodified form of constructionwith an interspace between the overlap and the overlapped parts. lReferring to the drawings, vwhich are somewhat. diagrammatic, theaeronautical propeller therein shown to illustrate a preferred form ofmy invention is to beconsidered as measuring 16 feet in diameter, thatis, with two 8 foot blades and to run at 900 R. P. M., with 1000 h. p.geared engine.

or cut at one-end to the proper blade outline including the ti and fromthe other end a central ongitudinal slot 5, is cut about 6 feet long,bifurcating the plate into two' branches or ton es 2, 2. The innercorner of each branch 1s then cut-away on a curvature running into theslit, as at 4, the cutaway edges subsequently constituting the outeredges of the overlapping branchesand len h of such p-art and then afterthe bend to ie in the same plane with each other,

provide a neat and desirable finish for the which plane is substantiallyat right-angles u to the plane of the unslit portion of the blade, andwith the outer edges 4, 4, of eachbranch brought to a, junction (asindicated in Figs. 2 and 3, and also lin Figs. 4, 5 and 6 of thecompleted device) withtheir inter-relations reversed, i. e., the formerslot-edges become the outer free edges. This arran ement provides acentral elongated and wide space 17, foi` reception of the hub structureand through which extends the axis of rotation, and the center of thisspace is 8 feet from the tips of the blades.

As the pair of blades are duplicates, Iin order to make the drawingsclear in Figs. 4 tol 10, I have marked the reference numeralsdesignating the various parts of the righthand blade, with a prime mark,thus 1', 2

tively shifted into positions in which their tips lie outwardly in linein substantially operative positions, which movements bring the prongsof each plate into contact with those of the other along the bends 3, 3,with the portions-,beyond the bends in overlapping contact with theadjacent or unslitfportions of the blades. The two branches/,of eachblade which thus overlap the unslitfportion of its blade-mate are thusdis osed on the same side ofthe propeller an may lie in close surfacecontact therewith. The overlapping branches of each blade are thenunited or attached securely to the other blade and particularly to theunslit portion of such overlapped blade, in any well known andconvenient manner to form a unit structure, such as by means of rivetsorbolts 6, which extend through holes 7, formed in each of the branchesand which are of an oblong shape with the long axis lying longitudinallyof the blades, to thereby relieve the connection from sustaining anypart of the centrifugal stress when the propeller is rotated.

This construction and arrangement results in an ag egate blade thicknessin the overgr thrust loads,

lap portions, double the `plate thickness, therefore in this case 15/8inches. Each composite blade is then carved or otherwise formed as a.unit to the desired'profiles, as shown particularly in Figs. 7, 8 and10. The resulting blades are composite for much of their width and asubstantial art of their lengths, in this case 5 feet, leavingthe outeror tip portion of the blade in this case, 3 feet long, non-composite ofa single layer of piece construction, as shown in cross-section Fig. 8,the blade part `1, continuing for the" full length of the blade whilethe overlap 2, falls short of that.

The overlapping art 2, may be disposed with an interspace tween it andthe over.

lalplped part 1, as shown in Figs. 9 and 10, in w ch case filler blocksor spools 15, may be used to partlyill the interspace and to' sustaintheclamping stress of bolts or securin means 6. This mterspace may beenclosed by an arching of the overlapv 2, to produce more camber.

In the central opening 17, is inserted a suitable metal hub 8, madepreferably of nickel steel, which may be secured to the propeller in anyconvenient well known manner. The tubular hub'herein shown comprises atubular member 12, having an internal key-way 11, to fit the engine;drive-shaft (not shown), and is provided with a fixed external attachingange 9, and a corresponding removable ange plate 10, which parts areshaped to conform to and snugly it the' contactlng surfaces of theblades, over which they extend for a considerable distance in the radialdirection. These attaching parts 9 and 10, of the hub, may be secured inplace by means of some of the bolts 7, 7, which se-v cure theoverlapping portions of the blades together. which is removable, issecured to the hub against torsional movements by means of suitablesplines orkeys.

The extremities of the v overla ping branches are tapered tosubstantially al eath-v gradation of angles for the required pitch.v

The1 entire propeller is then heat treated or age The resultingpropeller has several advantages. The central-lock thereof supports mostof the centrifugal stresses, which are at The upper attaching flange 10,v

maximum at the center, leaving, if preferred only a fraction of suchstresses to be sustained vby the means which secures the overlap to theblade, and this overlap will also balanceA a part of the centrifugalstress, and thus will reduce the stresses tending to `rupture thepropeller.

The blades, while thin relatively to their camberratio or the necessarytorsional rigidity, and yet the outer parts of the blade' towards thetips, that is, more than one-third of the blade length, which parts moveat the highest peripheral velocities .and are subject to the most severeoperative stresses, are

a single piece and solid. A favorable central orifice is provided forthehub by the oppositely disposed inter-twined bends 1n the bladebranches and the comparatively large space surrounding the hub reducesthe weig t ofthe propeller. The blades leave the hub et have profiles ofsufficient` region at angles of about 45 de ees,which p meets the.demands of most prope ler designs. The centrifugal force stresses of thehigh veformed with elongated locity blade ends, are carried integrallyby anA blade and secured thereto and formed to' merge therewith as aunit, said overlap being bifurcated b -a cut or longitudinal slit, eachbranch of said bifurcation being individually distorted by compoundbends to reverse the relative position of its edges and to straddle thecenter and to interlock withthe similar bends of the opposite blade bycontinuous contact leaving a substantial space for a hub,

and a hub inserted in said space and attached to said compoundpropeller.

2. An aeronautical propeller made fromV metal plates, said propellerhavingthin solid blades bifurcated at the rootsy and centrallyinterlocking each of the bifurcated roots overlapping oneof the blades asubstantial distance, and the bifurcations being so distorted for thepur ose of the interlock that the blade roots are rought into positionwith cross-sections at substantially degrees from the plane of rotation.

3. An aeronautical propeller havingseparate oppositely extendingbladeswith forked roots intertwined with each other and overlapping each otherto a substantial'extent so that the overlaps shall balance to asubstantial -degree the stress of centrifugal force.

4. In an aeronautical propeller, blades each having their inner endsforked and g prongs passing around opposite sides of the axisof'rotation and bent outwardly and then in a. plane substantially atright-angles to the portion from.

which the rongs start and parallel with the overla p portion of itsblade-mate, the bent part o the prongs of each blade intertwining withthat of its blade-mate, and means for.

and means for retaining the blades in assembled relation. v

6. In an aeronautical propeller, -opposite blades each having forkedinner ends with the prongs deformed and their free ends disposed in acommon plane with the plane of the space or slit betweenforks cuttingthe axis of rotation, the prongs of each blade interlocking with thoseof the other blade and overlapping a substantial portion of the blade,and means for securing the blades in assembled positions.

7. TheV method of forming a propeller which comprises `forming aplurality 'of blades each with prongs, then bending the prongs so thatthey are turned on themselves 'to such a degree as to bring intoabutting re. -lation the outer edges of said prongs, passing the prongof the fork ofl one blade into the space between fork pron s of itsblade-mate, and then relatively shitting the blades on each other sothat the fork prongs of 'each blade overlap a portion of the otherblade.

. 8. The herein described method of forming interlocking blades in apropeller, which consists in forming the inner end of each blade withprongs,.and then deforming or bending thev prongs so that they areturned on themselves to such a degree as to bring into abutting relationthe outer edges of said prongs. 9. For an aeronautical propeller a bladehaving the inner end thereof forked and havl ing the forks twistedAsubstantially at right angles to themain body of the blade, the orig-linally .outer edges of the forksbeing posi-f tioned adjacent to eachother.

10. In an aeronautical propeller, a hub, and

-New York and State of New York, this 19th day of December, A. D. 1928.

' SYLVANUS A. REED.

securing the prongs of each blade to its blademate. l 5. In anaeronautical propeller, blades each having their inner ends providedrwith branches overlapping its blade-mate for suhstantally half theradial length thereof, said branches being bent outwardly and thenextending in' a plane substantiallyl at rightp angles to the portionfrom which they arise and substantially parallel with the overlappedportion of its blade-mate, said branches of oneV blade beinginterlocked-with those of the other so that the bent parts thereof areintertwined substantially in contact whereby such parts mutually resistcentrifugal force during rotation of the propeller,

